/// <summary>
/// Constructor
/// </summary>
/// <param name="messageId">Message Id</param>
/// <param name="flow">Message flow inside inflight queue</param>
internal MqttMsgContextFinder(ushort messageId, MqttMsgFlow flow)
{
this.MessageId = messageId;
this.Flow = flow;
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="messageId">Message Id</param>
/// <param name="flow">Message flow inside inflight queue</param>
internal MqttMsgContextFinder(ushort messageId, MqttMsgFlow flow)
{
MessageId = messageId;
Flow = flow;
}
/// <summary>
/// Enqueue a message into the inflight queue
/// </summary>
/// <param name="msg">Message to enqueue</param>
/// <param name="flow">Message flow (publish, acknowledge)</param>
private void EnqueueInflight(MqttMsgBase msg, MqttMsgFlow flow)
{
// enqueue is needed (or not)
bool enqueue = true;
// if it is a PUBLISH message with QoS Level 2
if ((msg.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE) &&
(msg.QosLevel == MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE))
{
lock (this.inflightQueue)
{
// if it is a PUBLISH message already received (it is in the inflight queue), the publisher
// re-sent it because it didn't received the PUBREC. In this case, we have to re-send PUBREC
// NOTE : I need to find on message id and flow because the broker could be publish/received
// to/from client and message id could be the same (one tracked by broker and the other by client)
MqttMsgContextFinder msgCtxFinder = new MqttMsgContextFinder(((MqttMsgPublish)msg).MessageId, MqttMsgFlow.ToAcknowledge);
MqttMsgContext msgCtx = (MqttMsgContext)this.inflightQueue.Get(msgCtxFinder.Find);
// the PUBLISH message is alredy in the inflight queue, we don't need to re-enqueue but we need
// to change state to re-send PUBREC
if (msgCtx != null)
{
msgCtx.State = MqttMsgState.QueuedQos2;
msgCtx.Flow = MqttMsgFlow.ToAcknowledge;
enqueue = false;
}
}
}
if (enqueue)
{
// set a default state
MqttMsgState state = MqttMsgState.QueuedQos0;
// based on QoS level, the messages flow between broker and client changes
switch (msg.QosLevel)
{
// QoS Level 0
case MqttMsgBase.QOS_LEVEL_AT_MOST_ONCE:
state = MqttMsgState.QueuedQos0;
break;
// QoS Level 1
case MqttMsgBase.QOS_LEVEL_AT_LEAST_ONCE:
state = MqttMsgState.QueuedQos1;
break;
// QoS Level 2
case MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE:
state = MqttMsgState.QueuedQos2;
break;
}
// queue message context
MqttMsgContext msgContext = new MqttMsgContext()
{
Message = msg,
State = state,
Flow = flow,
Attempt = 0
};
lock (this.inflightQueue)
{
// enqueue message and unlock send thread
this.inflightQueue.Enqueue(msgContext);
}
}
this.inflightWaitHandle.Set();
}
private void EnqueueInflight(MqttConnection connection, MqttMsgBase msg, MqttMsgFlow flow)
{
// enqueue is needed (or not)
var enqueue = true;
// if it is a PUBLISH message with QoS Level 2
if (msg.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE && msg.QosLevel == MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE)
{
// if it is a PUBLISH message already received (it is in the inflight queue), the publisher
// re-sent it because it didn't received the PUBREC. In connection case, we have to re-send PUBREC
// NOTE : I need to find on message id and flow because the broker could be publish/received
// to/from client and message id could be the same (one tracked by broker and the other by client)
var msgCtxFinder = new MqttMsgContextFinder(msg.MessageId, MqttMsgFlow.ToAcknowledge);
var msgCtx = (MqttMsgContext)connection.InflightQueue.FirstOrDefault(msgCtxFinder.Find);
// the PUBLISH message is alredy in the inflight queue, we don't need to re-enqueue but we need
// to change state to re-send PUBREC
if (msgCtx != null)
{
msgCtx.State = MqttMsgState.QueuedQos2;
msgCtx.Flow = MqttMsgFlow.ToAcknowledge;
enqueue = false;
}
}
if (enqueue)
{
// set a default state
var state = MqttMsgState.QueuedQos0;
// based on QoS level, the messages flow between broker and client changes
switch (msg.QosLevel)
{
// QoS Level 0
case MqttMsgBase.QOS_LEVEL_AT_MOST_ONCE:
state = MqttMsgState.QueuedQos0;
break;
// QoS Level 1
case MqttMsgBase.QOS_LEVEL_AT_LEAST_ONCE:
state = MqttMsgState.QueuedQos1;
break;
// QoS Level 2
case MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE:
state = MqttMsgState.QueuedQos2;
break;
}
// [v3.1.1] SUBSCRIBE and UNSUBSCRIBE aren't "officially" QOS = 1
// so QueuedQos1 state isn't valid for them
if (msg.Type == MqttMsgBase.MQTT_MSG_SUBSCRIBE_TYPE)
{
state = MqttMsgState.SendSubscribe;
}
else if (msg.Type == MqttMsgBase.MQTT_MSG_UNSUBSCRIBE_TYPE)
{
state = MqttMsgState.SendUnsubscribe;
}
// queue message context
var msgContext = new MqttMsgContext()
{
Message = msg,
State = state,
Flow = flow,
Attempt = 0
};
// enqueue message and unlock send thread
connection.EnqueueInflight(msgContext);
// PUBLISH message
if (msg.Type == MqttMsgBase.MQTT_MSG_PUBLISH_TYPE)
{
if (msgContext.Flow == MqttMsgFlow.ToPublish &&
(msg.QosLevel == MqttMsgBase.QOS_LEVEL_AT_LEAST_ONCE ||
msg.QosLevel == MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE))
{
if (connection.Session != null)
{
connection.Session.InflightMessages.TryAdd(msgContext.Key, msgContext);
}
}
// to acknowledge and QoS level 2
else if (msgContext.Flow == MqttMsgFlow.ToAcknowledge &&
msg.QosLevel == MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE)
{
if (connection.Session != null)
{
connection.Session.InflightMessages.TryAdd(msgContext.Key, msgContext);
}
}
}
}
}
